1. Technical Field
The present invention relates in general to an improved downhole tool, and in particular to an improved surface-actuated release tool for downhole applications.
2. Description of the Prior Art
Downhole release tools for submersible pump bottom hole assemblies are well known in the art. Unfortunately, some of these devices require remote operation or actuation that requires electrical power to be available at the downhole assembly. Other prior art devices do not provide sufficient means for retrieving the equipment once it is released. Still other devices are limited to configurations that require the motor to be located either above the pump or below the pump. For example, in one prior art release tool (U.S. Pat. No. 5,419,399), a ball is dropped from the surface to pressurize the coiled tubing itself. In another prior art device, the release tool is electrically actuated and requires the use of a wire line cable. In addition, pressure from the drilling medium is also relied upon to help actuate the system. Thus, an improved apparatus and method for releasing a submersible pump bottom hole assembly is needed.
A submersible pump assembly has a release adapter on a string of coiled tubing. Power cables and a hydraulic capillary tube extend through the coiled tubing to the release adapter where each terminates at a coupling. The release adapter has a locking mechanism that is located in a chamber adjacent to a fishing neck at the upper end of the pump. The locking mechanism has a collet that is latched to the fishing neck. A piston captures the collet against the neck, and is restrained from movement by shear pins.
The locking mechanism is actuated from the surface by pumping hydraulic fluid down through the capillary tube to the chamber to stroke the piston downward and shear the pins. When the piston moves, the lower end of the collet releases the fishing neck and is free to be retracted axially upward into the wellbore toward the surface. As the coiled tubing lifts the release adapter away from the fishing neck, tension develops in the wires and tubing until those components detach from their respective couplings. After the unplugged assembly is raised to the surface, a fishing tool may be lowered to retrieve the remaining assembly on the clean and clear fishing neck.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.